1. Field of the Invention
This invention comprises a two-sided grab bucket comprising a U-shaped scoop carrier and two scoops, which are provided with crosspieces, which are welded to the inside surfaces of the upper edge portions of the side walls of the scoops and are pivoted to the legs of the scoop carrier on two spaced apart parallel axes, actuating levers, which are welded to the crosspieces, and a transversely extending hydraulic piston-cylinder unit, which is pivoted to and connects the free ends of said levers.
2. Description of the Prior Art
A problem arising in connection with two-sided grab buckets resides in that each scoop will be stressed in torsion, particularly when the cutting edges of the scoops are acted upon by different forces opposing the closing pressure or when stones or other objects are clamped between the cutting edges and cause the latter to be subjected to unbalanced loads.
A two-sided grab bucket which is of the type described first hereinbefore and has been disclosed in U.S. Pat. No. 4,405,167 is provided with means which increase the torsional stiffness of the grab bucket without substantially increasing its weight. To that end a tube is welded to the inside surfaces of the side walls of each scoop near its upper edge and is adapted to take up the torsional forces which act on the side walls of the scoops and tend to distort the same. But the stiffening of the scoops with tubes which are welded to the side walls of the scoops gives rise to difficulties regarding the pivotal mounting of the scoops because the tube should also be used for the pivotal mounting of the scoops so that there will be no need for additional pivots or stiffeners, and because the bearings should not protrude beyond the side walls of the scoops, which side walls determine the width of the grab bucket. Such protruding bearing elements might be damaged and constitute obstructions during the operation of the grab bucket. In the two-sided grab bucket disclosed in U.S. Pat. No. 4,405,167 the torsion-resisting tubes which connect the side walls of the scoops are provided near their ends with radial slots, which extend around part of the periphery of the tubes, and the legs of the scoop carrier extend through said slots and are formed with bearing bores so that the legs can be pivoted in the tubes and the side walls of the scoops by means of pivot pins inserted into the tubes. In the known two-sided grab bucket the tubes welded to the side walls of the scoops can effectively stiffen the scoops in spite of the peripheral slots in the tubes, but the mounting of the legs of the scoop carrier in the slotted portions of the torsion-resisting tubes is complicated and expensive.